The invention relates to improvements in a precision measuring apparatus of the type having a measuring scale, a scanning unit for scanning the scale, and a housing for supporting the scale and the scanning unit.
Such measuring instruments are generally known in the art. For example, West German Patent Application AS No. 26 43 304 shows a length measuring apparatus which utilizes a rigid strip of glass to form a guide for the scanning unit. The glass strip is mounted to the apparatus housing by an elastic adhesive. Furthermore, West German Patent PS No. 27 27 729 discloses a measuring apparatus of the above type in which the scale is mounted on an intermediate carrier and forms therewith a guide surface for the scanning unit.
The known measuring instruments however have some disadvantages, including complicated construction and difficulty of adjustment. The disadvantages become specially noticeable when the distances to be measured are relatively large.